Pancuronium Group Research Articles

Haemodynamic differences between pancuronium and vecuronium in an experimental pig model

ObjectiveTo compare baseline cardiovascular function in anesthetised pigs using either pancuronium or vecuronium as a neuromuscular blocker. Study designRetrospective, non-randomized comparison. AnimalsNorwegian Land Race pigs (Sus scrofa domesticus) weighing mean 42 ± SD 3 kg. MethodsOne hundred and sixteen animals from four different research protocols premedicated with identical doses of ketamine, diazepam, atropine and isoflurane, and anaesthetised with pentobarbital, fentanyl, midazolam and N2O were arranged into three uniform groups with respect to neuromuscular blocking agent: pancuronium bolus of 0.063 mg kg−1 followed by 0.14 mg kg−1 hour−1 (n = 54), low-dose vecuronium 0.4 mg kg−1/0.2 mg kg−1 hour−1 (n = 29) and high-dose vecuronium 0.6 mg kg−1/0.3 mg kg−1 hour−1 (n = 33). ResultsThe majority of cardiovascular parameters demonstrated no significant differences between groups. For heart rate, there was an overall group difference, p = 0.036. Dromotropy was low in the pancuronium group, with an increased normalised PR-interval compared to the high-dose vecuronium group, median 0.200 interquartile range (0.190, 0.215) versus 0.182 (0.166, 0.199), p < 0.05. Left ventricular compliance was increased in pancuronium-treated animals, demonstrated as a reduction in the nonlinear end-diastolic pressure volume relationship β compared to both vecuronium groups, 0.021 (0.016, 0.025) versus 0.031 (0.025, 0.046) and 0.031 (0.022, 0.048), p < 0.05. The linear end-diastolic pressure volume relationship EDPVRlin was reduced as well in the pancuronium group, compared to the low-dose vecuronium group, 0.131 (0.116, 0.169) versus 0.181 (0.148, 0.247), p < 0.05. ConclusionsThere are only minor haemodynamic differences when using pancuronium compared to vecuronium in the fentanyl-pentobarbital-midazolam-N2O anesthetised domestic pigs. Furthermore, increasing doses of vecuronium have minimal haemodynamic effects. Clinical relevanceExperimental studies in pigs using either pancuronium or vecuronium as a neuromuscular blocking agent are comparable with regard to cardiac and haemodynamic performance.

Assessment of Reversal Pattern of Neuromuscular Blockade: A Comparative Study Between Clinical and Instrumental Methods

Introduction: Delayed reverse from the effect of neuromuscular blockade and from the effect of anaesthesia is a concern among anaesthesiologists. Objectives: Objectives of the study were to compare reversal pattern of neuromuscular blockade by clinical and instrumental methods and to elicit reliable clinical parameters. Methods: This prospective study was carried out in CMH, Dhaka among 50 adult patients and reversal pattern of neuromuscular blockade was evaluated by clinical and instrumental methods among pancuronium group(Group-I) and rocuronium group(Group-II). All data were collected in data collection sheet and were compiled and analyzed by Student’s‘t’ test. Results: Clinical assessment was carried out by bedside test for muscular function &amp; instrumental assessment was carried out by nerve stimulator and Train of Four (TOF). In pancuronium group (Gp-I) clinically patient was reversed on average (6.19 ± 2.04 min) (mean±SD, n=25) earlier than instrumental method of which tidal volume was found less reliable. But in rocuronium group (Gp-II) instrumentally patient was reversed average (12.56 ± 3.41 min) (mean±SD, n=25) earlier than clinical method of assessing reversal, here also tidal volume was found less reliable among clinical variables. Conclusion: The study revealed that tidal volume is the less reliable among the clinical variables. In Group-I clinical reversal criteria for neuromuscular blockade were fulfilled earlier than that of instrumental method but in Group-II instrumental criteria were fulfilled earlier than clinical method. We should combine 2 or 3 clinical criteria for adequate reversal from neuromuscular blockade. DOI: http://dx.doi.org/10.3329/jafmc.v9i1.18725 Journal of Armed Forces Medical College Bangladesh Vol.9(1) 2013: 43-48

Study on Neuromuscular Blockade Action of Verapamil in Albino Rats

Calcium Channel Blockers (CCBs) are now widely employed in the treatment of cardiovascular diseases and peri operative hypertension. It has been reported that calcium channel blockers inhibit neuromuscular transmission. They have been shown to increase the neuromuscular blockade produced by neuromuscular blocking agents in in-vitro muscle nerve preparations. The present study is undertaken to demonstrate the effect of calcium channel blocker, verapamil on neuromuscular transmission in albino rats. To study the neuromuscular blockade action of verapamil in albino rats. Twenty four albino rats of either sex weigh 150-250gms are selected and are randomly divided into 4 equal groups. The experimental rats are divided into four groups of 6 rats each and they are given the following treatment. Group 1(Control) - Normal saline (1ml/ kg), Group 2 (Standard) - Pancuronium (0.04 mg/kg) Group 3-Verapamil (2.5mg/kg), Group 4-given Verapamil (10mg/kg). The time of onset of hind limb paralysis and total duration of recovery are noted using inclined screen method. Analysis of the results of group 3 that was received 2.5mg/kg of Verapamil, there was no onset of paralysis, in group 4 that received injection Verapamil 10mg/kg, showed neuromuscular blockade activity. The mean onset of hind limb paralysis was delayed compared to standard group and the mean duration of hind limb paralysis was shorter than standard group. It was statistically significant (P≤ 0.05). It is generally held that external calcium is not necessary for the contraction of mammalian skeletal muscle, the demonstration of inward calcium currents that can be abolished by CCBs in these muscles prompted to re-examine the effect of Verapamil on the neuromuscular transmission. The present study allows us to determine the neuromuscular blockade activity of Verapamil.

Avaliação do bloqueio neuromuscular residual e da recurarização tardia na sala de recuperação pós-anestésica

Residual postoperative paralysis impairs airway patency increasing the risk for postoperative complications. Anti-cholinesterase agents improve neuromuscular transmission by acetylcholine build up in the endplate. However, when there is no longer neostigmine effect, 'recurarization' is theoretically possible since the antagonist agent does not displace neuromuscular blocker from its action site. This study aimed at determining the degree of residual neuromuscular block in the Post Anesthetic Care Unit (PACU) and at observing whether patients receiving neostigmine presented the late 'recurarization' phenomenon.Participated in this study 119 adult patients who received neuromuscular blockers for different procedures. At PACU arrival, neuromuscular transmission has been quantified by acceleromyography, with stimulating electrodes placed over the ulnar nerve at the wrist, the train of four (TOF) was used with electrical current of 30mA at 15-minute intervals for a period of 120 minutes. Residual neuromuscular block was considered T4/T1 ratio below 0.9. Clinical symptoms suggesting residual neuromuscular block and vital signs were also recorded in the PACU. Descriptive measures, such as mean and absolute frequency were used for statistical analysis.Patients receiving pancuronium had a higher incidence of residual block, especially the elderly. Patients receiving neostigmine also presented an expressive percentage of residual curarization. There has been no late recurarization in both groups.The incidence of residual block was significantly higher in the pancuronium group. There has been no case of recurarization with neostigmine suggesting that this phenomenon has no clinical significance when patients have no signs of organ failure or co-morbidity impairing neuromuscular transmission.

Up-regulation of acetylcholine receptors during subchronic infusion of pancuronium is caused by a posttranscriptional mechanism related to disuse

Contrasting with the classic theory that competitive block of the acetylcholine receptor induces up-regulation of the receptor, recent studies show that irreversible block of acetylcholine receptors with alpha-bungarotoxin decreases acetylcholine receptor number within hours. This study investigated the early effects of competitive acetylcholine receptor block with the reversible, competitive muscle relaxant, pancuronium. Prospective, randomized, placebo-controlled experimental study. Healthy adult Sprague-Dawley rats. Animal laboratory in a university hospital. After internal review board approval, Sprague-Dawley rats were anesthetized and received pancuronium at a rate to completely suppress neuromuscular twitch. The control group received saline. Infusion times were 0, 3, 6, or 12 hrs (n = 8 per group). One sciatic nerve was stimulated to induce muscle twitch, and the other nerve remained unstimulated. Total acetylcholine receptor expression, as well as expression of messenger RNA of the five subunits, was assayed. There were no differences in acetylcholine receptor number between groups at time points 0, 3, and 6 hrs. At 12 hrs, acetylcholine receptor numbers in both the stimulated (35.2 +/- 4.8 fmol acetylcholine receptor/mg protein) and nonstimulated (38.3 +/- 4.8) pancuronium group, as well as the nonstimulated control saline group (37.5 +/- 4.6), were significantly increased compared with stimulated controls (27.6 +/- 4.0). Pancuronium did not potentiate the acetylcholine receptor up-regulation of the nonstimulated control group at 12 hrs. There were no changes in messenger RNA expression between groups. Infusion of the reversible competitive inhibitor pancuronium up to 12 hrs does not reduce acetylcholine receptor number and therefore contrasts with the irreversible acetylcholine receptor blocker alpha-bungarotoxin. This study documents that 12 hrs of disuse per se leads to an increased expression of the acetylcholine receptor number by a posttranscriptional mechanism that can be prevented by nerve-evoked muscle contraction.

Effect of atracurium or pancuronium on the anemic fetus during and directly after intra‐vascular intrauterine transfusion, A double blind randomized study

To determine the effect of atracurium or pancuronium on onset and duration of fetal paralysis, movements and heart rate parameters directly after transfusion, using computer analyzed fetal heart rate recording (c-FHR). Double blind randomized study of 23 RhD alloimmunized pregnant women requiring an intravascular intrauterine fetal blood transfusion (IUT) between 24 and 36 weeks. Atracurium was injected in 11 fetuses at 17 IUT's and pancuronium in 12 fetuses at 19 IUT's. For statistical analysis the Mann-Whitney test was used. No statistical differences were found in fetal heart rate and movements between both groups before transfusion. The fetal movements returned more rapidly in the atracurium group when compared to the pancuronium-group (median 24 vs. 57 min, range 6-55 vs. 4-220; (p<0.02). Fetal movements did not hamper the procedure in any case. The atracurium group showed significantly more fetal movements (p<0.01), more accelerations (0<0.05) but no significant reduction of fetal heart rate variability directly after transfusion which was in direct contrast to the pancuronium group. Neuromuscular blockade with atracurium produces sufficient paralysis for intrauterine transfusion with minimal disturbance of the parameters used to monitor fetal wellbeing after the procedure. Although the routine use of fetal paralysis during IUT may be questionable, we believe that when it is necessary the use of atracurium is the better choice.

Implementation of Pharmaceutical Practice Guidelines

Department of Anesthesiology, Duke University Medical Center, Box 3094, Durham, North Carolina 27710.In Reply:-Dr. Viby-Mogensen makes an important point, namely, that all significant complications do not occur immediately postoperatively. The paper to which he refers clearly documents the fact that inadequate neuromuscular blockade can occur. However, the doses of neostigmine given to patients in his pancuronium group, or the time interval after the last pancuronium dose, may have been insufficient. The authors documented this by noting that patients often arrived in the PACU with low train-of-four ratios. We believe that it is the adequacy of reversal, not the use of pancuronium per se, which influences the clinical outcome in the PACU and beyond.The practice guidelines we proposed regarding the use of pancuronium are sound as long as enough medication is administered to achieve appropriate reversal. Reversal should be monitored by standard train-of-four monitoring, making sure a twitch is present before reversal, and one should assess the ability to sustain tetanus for 5 s in addition to having 4/4 twitches of near equal magnitude (&gt; 0.7 T4/T1).David A. Lubarsky, M.D.Department of Anesthesiology; Duke University Medical Center; Box 3094; Durham, North Carolina 27710(Accepted for publication August 25, 1997.)

Is recovery of neuromuscular transmission complete after the use of neostigmine to antagonize block produced by rocuronium, vecuronium, atracurium and pancuronium?

To test if recovery of neuromuscular transmission is complete after the use of neostigmine under standardized conditions, we have measured adductor pollicis mechanical activity in response to 0.1 Hz (twitch height), train-of-four (TOF) and 100 Hz (RF 100 Hz) ulnar nerve stimulations. We studied 56 adult anaesthetized (thiopentone, fentanyl, nitrous oxide in oxygen) patients, allocated randomly to one of four groups (n = 14) to receive rocuronium (group Roc), vecuronium (group Vec), atracurium (group Atr) or pancuronium (group Pan). Recovery of neuromuscular transmission was studied for 15 min after neostigmine 40 micrograms kg-1 was given at 25% recovery of twitch height. Fifteen minutes after antagonism, the TOF ratio was 0.91 (SEM 0.01), 0.88 (0.02) and 0.92 (0.01) (ns), and RF 100 Hz was 0.78 (0.01), 0.79 (0.02) and 0.78 (0.01) (ns) respectively, in patients in groups Roc, Vec and Atr, respectively. In patients in group Pan, TOF ratio and RF 100 Hz were only 0.76 (0.01) and 0.33 (0.04) respectively (P < 0.01, one-way analysis of variance, Duncan's multiple classification range tests). In contrast with pancuronium, antagonism of rocuronium-, vecuronium- and atracurium-induced neuromuscular blocks produced a similar high degree of recovery of neuromuscular transmission.

Mivacurium When Precedent by Pancuronium Becomes a Long-acting Muscle Relaxant

To ensure rapid recovery of neuromuscular block, it might be useful to administer a short-acting relaxant after a long-acting one. Therefore, the interaction between pancuronium and mivacurium was investigated when mivacurium was administered during the recovery from pancuronium block. After written informed consent, 41 adult patients were studied during propofol/alfentanil/nitrous oxide/oxygen anesthesia. Neuromuscular function was monitored using an electromyographic (EMG) method. AFter a stable EMG calibration response, cumulative doses of pancuronium were given to establish a 95% neuromuscular block. In the control group, and ED95 dose of 100 microg/kg mivacurium was administered instead of pancuronium. When the EMG response after pancuronium or mivacurium had recovered to 25% of the baseline, a single randomized intravenous bolus dose of 10 or 70 microg/kg mivacurium was given. Thereafter, spontaneous recovery of the neuromuscular function was recorded. The time from pancuronium until T1 25% EMG recovery was 38 +/- 12 min (mean +/- SD). The respective times after 10 or 70 microg/kg mivacurium were 28 +/- 8 and 54 +/- 7 min in the pancuronium group or 3 +/- 1 (n=3) and 10 +/- 4 min in the mivacurium group (P=0.0001). Times to 95% EMG recovery after 10 or 70 microgm/kg mivacurium were 77 +/- 14 and 97 +/- 16 min in the pancuronium group and 11 +/- 3 and 20 +/- 7 min in the mivacurium group, respectively (P<0.0001). Recovery indexes after 10 or 70 microg/kg mivacurium group, respectively (P<0.0001). Recovery indexes after 10 or 70 microg/kg mivacurium wre 26 +/- 4 and 22 +/- 6 min in the pancuronium group or 7 +/- 3 (n=3) and 5+/- 2 min in the mivacurium group, respectively (P<0.0001). Times from the administration of 10 or 70 microg/kg mivacurium until train-of-four ration 0.7 were 94 +/- 16 and 111 +/- 14 min in the pancuronium group and 12 +/- 4 and 22 +/- 8 min in the mivacurium group, respectively (P<0.0001). After pancuronium, mivacurium is not a short acting neuromusclar blocking agent.

The relationship between hyperthermia and duration of action of muscle relaxants

This project is based on the hypothesis that induced hyperthermia may prevent or treat the prolonged muscular relaxation caused by intraoperative hypothermia or by unknown origin. In some researches, one of the causes of postoperative respiratory depression is residual curarization which is usually resulted from hypothermia. But, there is no articles about the twiteh response in hyperthermia. The 10 mongrel dog with no muscular, renal or hepatic disease were classfied into 3 groups according to the type of muscle relaxants, atracurium group, pancuronium group and norcuron group. In each case, induced hyperthermia was applied on one side and normothermia was maintained on the other side. Muscular twitch response from the TOF stimulation was recorded. This experiment was repeated with tourniquet application in order to avoid the effect of systemic circulation. The muscular twitch response appeared faster in hyperthermia group than in normothermia group regardless of the type of muscle ralaxants. Now, therefore, we can utilize the results by inducing hyperthermia to treat and prevent the postoperative hypoxia caused by intraoperative hypothermia as well as excessive use or inade- quate reverse of muscle relaxants.

Rapid-sequence intubation of head trauma patients: Prevention of fasciculations with pancuronium versus minidose succinylcholine

Fasciculations during rapid-sequence intubation may lead to increased intracranial pressure and emesis with aspiration. Standard rapid-sequence intubation requires a nondepolarizing blocking agent before succinylcholine administration. Prevention of fasciculations during rapid-sequence intubation of head trauma patients can be accomplished as safely and effectively with minidose succinylcholine as with a defasciculating dose of pancuronium. A prospective, randomized, double-blind study. An inner-city county trauma center with 70,000 patient visits per year. Sequential adult head trauma patients requiring rapid-sequence intubation who had no contraindications to succinylcholine or pancuronium. Each head trauma patient requiring rapid-sequence intubation who met the inclusion criteria received standard rapid-sequence intubation maneuvers and lidocaine (1 mg/kg) IV. Patients were randomized to receive either minidose succinylcholine (0.1 mg/kg) or pancuronium (0.03 mg/kg) IV one minute prior to the full paralytic dose of succinylcholine (1.5 mg/kg) IV. Fasciculations were recorded using a graded visual scale. Of 46 patients, eight of 19 (42%) in the pancuronium group and six of 27 (22%) in the succinylcholine group experienced fasciculations. No statistically significant difference in fasciculations was detected between the two groups using chi 2 analysis. Complete relaxation of the cords was present in all but two patients, one in each group. No patient in either group experienced emesis or significant dysrhythmias. Pretreatment with minidose succinylcholine causes no greater incidence of fasciculations than pancuronium in rapid-sequence intubation of head trauma patients in an ED setting. Thus succinylcholine may be used as the sole paralytic agent in rapid-sequence intubation of head trauma patients.

Effects of pancuronium bromide on cerebral blood flow changes during seizures in newborn pigs.

We investigated the effects of pancuronium bromide pretreatment on cerebral blood flow (CBF) during bicuculline-induced seizures in anesthetized piglets. Arterial blood pressure, gases, pH, cerebral electrocortical activity, and CBF (radioactive microsphere) were monitored at baseline, 10 min after administration of pancuronium (0.3 mg/kg i.v.; n = 9) or vehicle (normal saline; n = 8), and again at 5, 15, and 60 min after bicuculline (3 mg/kg i.v.). No change in CBF from baseline was observed at 10 min after either saline or pancuronium treatment, before induction of seizures. In the saline group, CBF was 36 +/- 3 mL.min-1.100 g-1 before bicuculline and increased to 166 +/- 24 and 205 +/- 35 mL.min-1.100 g-1 at 5 and 15 min, respectively, after bicuculline, returning toward baseline by 60 min. In the pancuronium group at 5 min after bicuculline, CBF increased from 45 +/- 7 to 169 +/- 26 mL.min-1.100 g-1, but fell to 88 +/- 17 mL.min-1.100 g-1 at 15 min in contrast to saline-treated piglets. Also, at 15 min of seizures, differences between groups were observed in arterial blood pressure, gases, and pH. Although these variables were in the normal range with pancuronium treatment, the saline-treated animals had increased arterial blood pressure (81 +/- 6 mm Hg) and PCO2 (6 +/- 0.4 kPa) and decreased PO2 (7 +/- 0.5 kPa) and pH (6.91 +/- 0.06). Electrocortical activity was abnormal during seizures in both groups. At 60 min, reversal to normal activity was observed in six of nine pancuronium-treated animals versus two of eight saline-treated animals. These data suggest that pancuronium limits cerebral hyperemia during prolonged seizures by attenuating increases in blood pressure as a result of elimination of skeletal muscle activity. This leads to minimal alteration of arterial PCO2, PO2, and pH during seizures.

Effects of Atracurium and Pancuronium on the Oculocardiac Reflex in Children

The authors compare the effect of two muscle relaxants, atracurium and pancuronium, on the bradycardia resulting from the oculocardiac reflex during eye surgery for strabismus in children. Two groups, each composed of 15 children, received either pancuronium or atracurium during strabismus operations. Heart rate and rhythm were observed at several points during the operations, and the changes that occurred in the two groups were compared. We found that the incidence and severity of the bradycardia, the incidence of dysrhythmias, and the need for atropine administration were significantly greater in the atracurium group than in the pancuronium group.

Hemodynamic responses to pancuronium and vecuronium during high-dose fentanyl anesthesia for coronary artery bypass grafting

The hemodynamic and electrocardiographic (ECG) effects of pancuronium and vecuronium were compared during high-dose fentanyl anesthesia for coronary artery bypass grafting (CABG) surgery. Forty-eight morphine-scopolamine premedicated patients scheduled for elective CABG were anesthetized with fentanyl (100 μ/kg) in divided doses, and either of two muscle relaxants, pancuronium (n = 26; 0.10 mg/kg) or vecuronium (n = 22; 0.09 mg/kg). Hemodynamic data, blood gas samples, and ECG tracings were obtained at the following intervals: (1) control; (2) prior to intubation; (3) 1 minute after intubation; (4) prior to sternotomy; and (5) 1 minute after sternotomy. In the pancuronium group, heart rate (HR), cardiac index (CI), and rate-pressure product (RPP) were increased after induction of anesthesia and following intubation. Eleven patients (42.3%) displayed ischemic ST segment changes. Four patients in this group developed tachycardia and hypertension to an extent requiring pharmacological intervention. Vecuronium-treated patients displayed no increases in HR, MAP, and RPP, and a decrease in CI. Only one patient (5.6%) developed evidence of ischemic ECG changes. Four patients in the vecuronium group, all receiving preoperative β-blocker therapy, became hypotensive and bradycardic after the induction of anesthesia. The present investigation confirms the increased incidence of myocardial ischemia during high-dose fentanyl-pancuronium anesthesia. Although vecuronium was associated with fewer myocardial ischemic changes, the occurrence of bradycardia and hypotension in some patients receiving preoperative β-adrenergic blocking drugs remains a concern.

Does Perioperative Tactile Evaluation of the Train-of-four Response Influence the Frequency of Postoperative Residual Neuromuscular Blockade?

The authors conducted a randomized controlled clinical trial to evaluate the usefulness of perioperative manual evaluation of the response to train-of-four (TOF) nerve stimulation. A total of 80 patients were divided into four groups of 20 each. For two groups (one given vecuronium and one pancuronium), the anesthetists assessed the degree of neuromuscular blockade during operation and during recovery from neuromuscular blockade by manual evaluation of the response to TOF nerve stimulation. In the other two groups, one of which received vecuronium and the other pancuronium, the anesthetists evaluated the degree of neuromuscular blockade solely by clinical criteria. The use of a nerve stimulator was found to have no effect on the dose of relaxant given during anesthesia, on the need for supplementary doses of anticholinesterase in the recovery room, on the time from end of surgery to end of anesthesia, or on the incidence of postoperative residual neuromuscular blockade evaluated clinically. The median (and range of) TOF ratios recorded in the recovery room were 0.75 (0.33-0.96) and 0.79 (0.10-0.97) in the vecuronium groups monitored with and without a nerve stimulator, respectively. These ratios were significantly higher than those found in the pancuronium groups, which wre 0.66 (0.06-0.90) and 0.63 (0.29-0.95), respectively. However, no difference was found between the vecuronium and pancuronium groups in the number of patients showing clinical signs of residual neuromuscular blockade, as evaluated by the 5-s head-lift test.(ABSTRACT TRUNCATED AT 250 WORDS)

The influence of pancuronium and vecuronium combined with balanced anaesthesia on haemodynamics and myocardial oxygen balance

The effects of the non-depolarizing muscle relaxants pancuronium (Pancuronium) and vecuronium (Norcuron) (0.1 mg/kg) on myocardial blood flow, myocardial oxygen consumption, myocardial lactate balance, cardiovascular dynamics and electrocardiogram were studied in two groups of eight patients undergoing coronary artery bypass surgery. After induction of anaesthesia with 0.015-0.02 mg/kg flunitrazepam, isoflurane (0.5 vol%) and N2O/O2 (l/l), neuromuscular blockade was induced with pancuronium or vecuronium (0.1 mg/kg) combined with a single dose of 0.005 mg/kg fentanyl. Haemodynamic measurements were performed and the electrocardiogram was recorded before anaesthesia, in steady-state anaesthesia, after relaxation with pancuronium or vecuronium combined with fentanyl, and after intubation. The haemodynamic data consisted of heart rate, cardiac index, stroke volume index, mean arterial pressure, total peripheral resistance, pulmonary arterial pressure, pulmonary capillary wedge pressure, right atrial pressure, myocardial blood flow, coronary vascular resistance, myocardial oxygen consumption, coronary aterio-mixed venous content difference, myocardial lactate extraction and rate pressure product. In the vecuronium group, heart rate decreased significantly more (21%) than in the pancuronium group (9%). Therefore myocardial oxygen consumption (48% resp. 35%) and coronary blood flow (31% resp. 18%) decreased more in the vecuronium than in the pancuronium group. The higher metabolic demand in the pancuronium group induced a significantly lower coronary vascular resistance, because the decrease in coronary perfusion pressure was similar in both groups. None of the other haemodynamic parameters differed significantly in either patient group. We did not observe ST-segment depressions or elevations in the ECG, increases in PCWP or myocardial lactate production. Therefore extended myocardial ischaemia can be excluded in our patients who received pancuronium or vecuronium for neuromuscular blockade.

Muscle relaxants change myocardial metabolism in patients with ischemic heart disease during high‐dose fentanyl anesthesia

Although not unanimously accepted, high-dose fentanyl anesthesia has been associated with hemodynamic stability and little derangement of myocardial oxygen balance. This apparent inconsistency inspired us to investigate the effects on cardiac function and myocardial metabolism of stepwise increasing doses of fentanyl, accumulating to 15, 30, and 50 micrograms.kg-1, with the least possible interference from other drugs. Subjects were unpremedicated patients with ischemic cardiac disease scheduled for coronary artery bypass grafting or major vascular surgery. In an initial study employing succinylcholine for muscle relaxation, we found that heart rate (HR), coronary sinus blood flow (CSF) and coronary vascular resistance (CVR) remained unchanged, while systemic arterial pressure (SBP), rate-pressure product (RPP), coronary perfusion pressure (CPP) and left ventricular work (LVW) decreased. Myocardial uptake of oxygen (MVO2) and free fatty acids (FFA) both decreased in a dose-dependent manner. Arterial lactate concentration and myocardial lactate uptake both increased. These findings opposed the postinduction myocardial ischemia noted by some other investigators. In most of these studies pancuronium bromide had been used for muscle relaxation. Since the latter agent has been claimed to increase cardiac work, a second group of correspondingly diseased patients was studied in which succinylcholine was replaced by pancuronium bromide. In this group HR, RPP, CSF and MVO2 all increased at the lowest dose of fentanyl and HR additionally also at 30 micrograms.kg-1. The cardiac index was higher in the pancuronium group at the lowest and middle dose steps of fentanyl. Lactate uptake decreased with higher doses of fentanyl and relative myocardial lactate extraction declined.(ABSTRACT TRUNCATED AT 250 WORDS)

Atracurium, Vecuronium, and Pancuronium Do Not Alter the Minimum Alveolar Concentration of Halothane in Humans

The authors studied 64 unpremedicated, healthy surgical patients, aged 42 +/- 14 yr, to determine the effects of atracurium, vecuronium, and pancuronium on the minimum alveolar concentration (MAC) of halothane. Anesthesia was induced using halothane/nitrous oxide/oxygen via a mask without the administration of other drugs. Nitrous oxide was discontinued, the trachea was intubated without prior administration of neuromuscular blocking drugs, and anesthesia was maintained with halothane in oxygen. Participating patients were assigned to one of five groups: 1) no neuromuscular blocking drug (control group, n = 9); 2) atracurium 0.5 mg/kg (n = 10); 3) atracurium 1.0 mg/kg (n = 15); 4) vecuronium 0.1 mg/kg (n = 20); or, 5) pancuronium 0.1 mg/kg (n = 10). Tourniquets, inflated to 300 mmHg immediately before iv administration of neuromuscular blocking drug and 15-30 min prior to skin incision, were used to isolate extremities from circulating neuromuscular blocking drug in all patients. A positive response to stimulation was defined as movement of at least one extremity occurring distal to the tourniquet within 1 min following skin incision. The first patients in the control and atracurium groups were studied at an end-tidal halothane concentration of 0.95%. The first patient in the pancuronium group was studied at a halothane concentration of 0.75%, and the first patient in the vecuronium group at 0.70%. Subsequent patients were studied at end-tidal halothane concentrations 0.10% above or below that of the preceding patient, depending on the presence or absence of movement with skin incision. Control MAC for halothane was 0.74% +/- 0.09% (mean +/- SEM).(ABSTRACT TRUNCATED AT 250 WORDS)

Combination of Pancuronium and Metocurine

Combination of pancuronium and metocurine or pancuronium and d-tubocurarine produces potentiation of neuromuscular blocking effects such that administration of relatively small doses of these drugs can yield clinically effective neuromuscular blockade. The clinical characteristics of the block produced in A.S.A. class I-II patients during N2O-narcotic-thiopental anesthesia by the pancuronium-metocurine combination at the calculated ED95 (N = 8) and at twice the ED95 (N = 9) were compared with the block produced by pancuronium alone at its ED95 (N = 20) and at twice the ED95 (N = 6). Onset time (from drug injection to 95% twitch suppression) and the maximum twitch depression achieved were comparable between corresponding groups, but the 25% recovery time (from drug injection to 25% recovery of twitch height) was significantly shorter in the groups that received the pancuronium-metocurine combination. Furthermore, at twice the ED95, heart rate increased significantly more in the pancuronium group than in the pancuronium-metocurine combination group. Mean systemic blood pressure did not change significantly in either group. We conclude that patients given a combination of pancuronium and metocurine in large doses experience less hemodynamic change and more rapid recovery of neuromuscular function than do patients given equivalent doses of pancuronium alone.

COMPARISON OF HAEMODYNAMIC EFFECTS OF METOCURINE AND PANCURONIUM IN PATIENTS WITH CORONARY ARTERY DISEASE

The haemodynamic effects of large bolus doses of metocurine 0.45 mg kg-1 and pancuronium 0.1 mg kg-1 were compared in patients with coronary artery disease anaesthetized with diazepam, anileridine and nitrous oxide. Hypotension occurred more frequently after metocurine and was a result of a decrease in systemic vascular resistance. After pancuronium there was no increase in arterial pressure or heart rate, but a small increase in cardiac index. The decrease in heart rate after metocurine was the principal cause of the statistically significant difference in cardiac index between the two groups. Contrary to previous findings, metocurine did not attenuate circulatory responses to tracheal intubation. During surgical stimulation, two of the 10 patients of the pancuronium group developed significant ST segment depression and three patients had a rate-pressure product greater than 12 000 mm Hg beat min-1. However, the difference in rate-pressure product between the groups was not statistically significant.